LATIN DICTIONARYLexicon Latīnum
prefix

si-

si-
Classical[siː]Ecclesiastical[si]

Meaning

  1. morphemeUsed to derive irrealis conditional adjectives, adverbs and pronouns.
    quis (“who”) → sīquis (“if who”)
    unde (“whence”) → sīcunde (“if whence”)

Origins

From sī (“if”).

Quick answers

What does si- mean in Latin?
si-, a prefix, means “Used to derive irrealis conditional adjectives, adverbs and pronouns.”.
How do you pronounce si-?
In classical Latin, [siː]; in ecclesiastical (church) Latin, [si].